This invention is directed to a device for denesting stacked articles particularly nested stacks of cup trays.
A variety of sauces and condiments are packaged for the fast food industry in individual serving cups. These cups are designed to hold a single serving of the sauce or condiment. The cups are dispensed individually to the consumer at the point of purchase of a product.
The cups are formed of a body having a reservoir for holding the contents. The body further includes a flange that is integrally formed with the reservoir. A lid is sealed over the flange to maintain the integrity of the contents of the cup prior to dispensing to the consumer. The lid can be pealed away from the flange to expose the contents in the cup reservoir for consumption by the consumer.
These cups are filled with product and sealed with a lid on machines generally identified as cup fill and seal packaging machines. For use with a fill and seal cup packaging machine, the cups initially are formed in a joined matrix or "cup tray" by vacuum forming a sheet of a suitable material such as polyethylene or the like. Typically the matrix of the cup tray has, for example, 4 by 5 or 5 by 5 rows and columns of cups arranged in a two dimensional matrix. The cup trays are loaded on the cup fill and seal packaging machine for loading with product and sealing with a lid. After filling and sealing, the individual cups in the matrix or tray are then separated from one another on the cup packaging machine. The separated cups are bulk packaged and dispensed to a retail outlet for ultimately dispensing to consumers.
For moving and supporting the cups on the cup packaging machine, the cup packaging machine utilizes a continuous belt formed of individual linked belt segments. Cup trays are located on the continuous belt by loading the cup trays onto the continuous belt such that the cup bodies fit into depressions on adjacent linked segments of the continuous belt. The belt then moves the cup bodies under the appropriate filling, sealing and cutting heads of the packaging machine.
Generally the cups trays for use on the cup packaging machine are formed at a different location by a manufacture specializing in vacuum forming of the same. They are then shipped in a stacked nested state, that is, stacked one upon another, to a product packager for use on a cup fill and seal packaging machine. To stack and nest the cup trays the bodies of the cups of an overlying tray are inserted into the bodies of the cups of an underlying tray. United States design patent D-289,854 shows a typical cup tray or cup matrix as formed by vacuum forming and ready for loading into a cup packaging machine.
For releasing from the vacuum forming mold and also for facilitating stacking, the cup bodies of a cup tray are formed such that their sides slope or draft at an angle. This allows the cup bodies to be both easily released from the mold and to be nested tightly together in stacking the trays for minimizing the volume for shipping purposes between the vacuum former and the product packager. Because the cup bodies are nested into one another, two adjacent cup trays can frictionally adhere to one another making it difficult to separate the same for loading onto a cup packaging machine.
At the present time two ways are known for loading the cup trays onto the continuous belt of the packaging machine. The first of these is hand loading. This requires an operator to be present at the packaging machine at all times to remove a cup tray from a stack of the same and load them one at a time onto the continuous belt of the packaging machine. This, of course, is very labor intensive as well as being very monotonous work for the operator.
The second method for loading the cup trays onto the continuous belt of the packaging machine utilizes a mechanical device for separating, conveying and dispensing the nested stacked cup trays. This device incorporates suction cups, moving arms, retention fingers and other mechanical components. Operation of this devices requires an arm having suction cups thereon to move over a stack of nested cup trays and then insert its suction cups into the cup bodies of the top member of the stack of cup trays. Suction is applied to grip that top cup tray. Meanwhile the totality of the stack is held by spring fingers such that (and hopefully) only one of the cup trays, the top cup tray, will be lifted from the stack by the suction cups and arms. Once freed from the stack the cup tray must then be moved from the stack to a position for loading onto the continuous belt of the packaging machine. Once in position vacuum must be removed to drop the cup tray onto the continuous belt and the arm must be swung back to pick up the next cup tray.
The above described mechanism is very complicated. It requires many moving parts and continuous formation and release of a vacuum. Depending upon the frictional fit between adjacent cup trays in a stack, the frictional fingers which attempt to retain all but one cup tray during the vacuum denesting process sometimes falter and allow for the simultaneous withdrawal of several trays still tightly frictionally adhering to one another. The still nested stack of two or more trays are then placed in the segments of the continuous belt of the packaging machine. Placement of more than one vertically stacked cup tray in the segments of the continuous belt renders the height of the cups in those segments of the continuous belt greater than that allowed by the working clearance between the cups and the various filling, sealing and cutting heads of the packaging machine. This can cause jams in the machine and other unexpected and undesirable problems.
Since fill and seal cup packaging machines operate at high speeds and because they dispense food products that must be packaged in a sanitary environment, any jamming or other erratic operation of the cup packaging machine can slow down the overall packaging process or, if spillage occurs, may require shutting down the machine to clean and resanitize the machine before further processing can be commenced.